Method for simultaneously removing multiple conductive materials from microelectronic substrates

ABSTRACT

A method and apparatus for simultaneously removing conductive materials from a microelectronic substrate. A method in accordance with one embodiment of the invention includes contacting a surface of a microelectronic substrate with an electrolytic liquid, the microelectronic substrate having first and second different conductive materials. The method can further include controlling a difference between a first open circuit potential of the first conducive material and a second open circuit potential of the second conductive material by selecting a pH of the electrolytic liquid. The method can further include simultaneously removing at least portions of the first and second conductive materials by passing a varying electrical signal through the electrolytic liquid and the conductive materials. Accordingly, the effects of galvanic interactions between the two conductive materials can be reduced and/or eliminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the following pending U.S. PatentApplications, all of which are incorporated herein by reference; Ser.No. 09/651,779 (Attorney Docket 10829.8515US), filed Aug. 30, 2000; Ser.No. 09/651,808 (Client Docket 00-0036), filed Aug. 30, 2000; Ser. No.09/653,392 (Client Docket 00-0130), filed Aug. 31, 2000; Ser. No.09/888,084 (Attorney Docket 10829.8515US1), filed Jun. 21, 2001; Ser.No. 09/887,767 (Attorney Docket 10829.8515US2), filed Jun. 21, 2001; andSer. No. 09/888,002 (Attorney Docket 10829.8515US3) filed Jun. 21, 2001.Also incorporated herein by reference are the following U.S. PatentApplications filed simultaneously herewith: Ser. No. 10/230,970(Attorney Docket 10829.8515US6); Ser. No. 10/230,972 (Attorney Docket10829.8515US7); Ser. No. 10/230,973 (Attorney Docket 10829.8515US8);Ser. No. 10/230,463 (Attorney Docket 10829.8672US); and Ser. No.10/230,628 (Attorney Docket 10829.8673US).

TECHNICAL FIELD

The present disclosure is directed toward methods and apparatuses forsimultaneously removing multiple conductive materials frommicroelectronic substrates.

BACKGROUND

Microelectronic substrates and substrate assemblies typically include asemiconductor material having features, such as memory cells, that arelinked with conductive lines. The conductive lines can be formed byfirst forming trenches or other recesses in the semiconductor materialand then overlaying a conductive material (such as a metal) in thetrenches. The conductive material is then selectively removed to leaveconductive lines or vias extending from one feature in the semiconductormaterial to another.

FIG. 1 is a partially schematic illustration of a portion of amicroelectronic substrate 10 having a conductive line formed inaccordance with the prior art. The microelectronic substrate 10 includesan aperture or recess 16 in an oxide material 13. A barrier layer 14,formed from materials such as tantalum or tantalum compounds, isdisposed on the microelectronic substrate 10 and in the aperture 16. Aconductive material 15, such as copper, is then disposed on the barrierlayer 14. The barrier layer 14 can prevent copper atoms from migratinginto the surrounding oxide 13.

In a typical existing process, two separate chemical-mechanicalplanarization (CMP) steps are used to remove the excess portions of theconductive material 15 and the barrier layer 14 from the microelectronicsubstrate 10. In one step, a first slurry and polishing pad are used toremove the conductive material 15 overlying the barrier layer 14external to the aperture 16, thus exposing the barrier layer 14. In aseparate step, a second slurry and a second polishing pad are then usedto remove the barrier layer 14 (and the remaining conductive material15) external to the aperture 16. The resulting conductive line 8includes the conductive material 15 surrounded by a lining formed by thebarrier layer 14.

One drawback with the foregoing process is that high downforces aretypically required to remove copper and tantalum from themicroelectronic substrate 10. High downforces can cause other portionsof the microelectronic substrate 10 to become dished or eroded, and/orcan smear structures in other parts of the microelectronic substrate 10.A further drawback is that high downforces typically are not compatiblewith soft substrate materials. However, it is often desirable to usesoft materials, such as ultra low dielectric materials, around theconductive features to reduce and/or eliminate electrical couplingbetween these features.

SUMMARY

The present invention is directed toward methods and apparatuses forsimultaneously removing multiple conductive materials from amicroelectronic substrate. A method in accordance with one aspect of theinvention includes contacting a surface of a microelectronic substratewith an electrolytic liquid, the microelectronic substrate having afirst conductive material and a second conductive material differentthan the first. The method can still further include controlling anabsolute value of a difference between a first open circuit potential ofthe first conductive material and a second open circuit potential of thesecond conductive material by selecting a pH of the electrolytic liquid.The method can further include simultaneously removing at least portionsof the first and second conductive materials by passing a varyingelectrical signal through the electrolytic liquid and the conductivematerials while the electrolytic liquid contacts the microelectronicsubstrate.

In a further aspect of the invention, wherein the first conductivematerial includes tungsten and the second conductive material includescopper, the method can include controlling an absolute value of adifference between the first open circuit potential and the second opencircuit potential to be about 0.50 volts or less by selecting the pH ofthe electrolytic liquid to be from about 2 to about 5. The conductivematerials can be removed simultaneously by passing an electrical signalfrom a first electrode spaced apart from the microelectronic substrate,through the electrolytic liquid to the first and second conductivematerials and from the first and second conductive materials through theelectrolytic liquid to a second electrode spaced apart from the firstelectrode and spaced apart from the microelectronic substrate.

A method in accordance with another aspect of the invention includesproviding a microelectronic substrate having a first conductive materialand a second conductive material different than the first. The methodcan further include disposing on the microelectronic substrate anelectrolytic liquid having a pH that controls a difference between afirst open circuit potential of the first conductive material and asecond open circuit potential on the second conductive material. Themethod can further include simultaneously removing at least portions ofthe first and second conductive materials by passing a variableelectrical signal through the electrolytic liquid and the conductivematerials while the electrolytic liquid contacts the microelectronicsubstrate.

An electrolytic liquid in accordance with another embodiment of theinvention can include a liquid carrier and an electrolyte disposed inthe liquid carrier. The electrolyte can be configured to transmitelectrical signals from an electrode to the first and second conductivematerials of the microelectronic substrate. A pH of the electrolyticliquid can be from about 2 to about 5.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic, cross-sectional view of a portion of amicroelectronic substrate having multiple conductive materials processedin accordance with the prior art.

FIGS. 2A-2C are partially schematic, cross-sectional illustrations of aportion of a microelectronic substrate having multiple conductivematerials processed in accordance with an embodiment of the invention.

FIG. 3 is a partially schematic, cross-sectional view of a portion of amicroelectronic substrate having multiple conductive materials processedin accordance with another embodiment of the invention.

FIG. 4 is a partially schematic illustration of an apparatus forelectrolytically removing conductive materials from a microelectronicsubstrate in accordance with an embodiment of the invention.

FIG. 5 is a partially schematic illustration of an apparatus forelectrolytically removing conductive materials from a microelectronicsubstrate in accordance with another embodiment of the invention.

FIG. 6 is a partially schematic illustration of an apparatus forelectrolytically, chemically-mechanically and/orelectrochemically-mechanically removing conductive material from amicroelectronic substrate in accordance with still another embodiment ofthe invention.

FIG. 7 is a partially schematic, isometric view of a portion of anembodiment of the apparatus shown in FIG. 6.

FIG. 8 is a partially schematic, isometric illustration of a portion ofan apparatus for removing conductive material from a microelectronicsubstrate in accordance with yet another embodiment of the invention.

FIG. 9 is a schematic illustration of a waveform for electrolyticallyprocessing a microelectronic substrate in accordance with still anotherembodiment of the invention.

DETAILED DESCRIPTION

The present disclosure describes methods and apparatuses for removingconductive materials from a microelectronic substrate. The term“microelectronic substrate” is used throughout to include a substrateupon which and/or in which microelectronic circuits or components, datastorage elements or layers, and/or micro-mechanical elements arefabricated. Features in the substrate can include submicron features(having submicron dimensions ranging from, for example, 0.1 micron to0.75 micron) such as trenches, vias, lines and holes. It will beappreciated that several of the details set forth below are provided todescribe the following embodiments in a manner sufficient to enable aperson skilled in the relevant art to make and use the disclosedembodiments. Several of the details and advantages described below,however, may not be necessary to practice certain embodiments of theinvention. Additionally, the invention can include other embodimentsthat are within the scope of the claims but are not described in detailwith respect to FIGS. 2A-9.

One approach for addressing some of the drawbacks described above withreference to FIG. 1 is to remove conductive materials from themicroelectronic substrate with electrolytic processes. Accordingly, avoltage is applied to the conductive material in the presence of anelectrolytic liquid to remove the conductive material. However, manyexisting electrolytic liquids cannot simultaneously remove copper andtantalum, once the tantalum barrier layer has been exposed. Accordingly,chemical-mechanical planarization (CMP) techniques are typically used toremove the exposed tantalum barrier layer and the adjacent coppermaterial. However, this approach typically re-introduces the highdownforces that the initial electrolytic process was intended to avoid.Accordingly, another approach has been to replace the tantalum barrierlayer with a tungsten barrier layer. However, tungsten (and tungstencompounds) typically form a galvanic couple with copper, which resultsin one or the other of these materials corroding and dissolving at anuncontrolled rate. The following disclosure describes methods andapparatuses for overcoming this drawback.

FIG. 2A is a partially schematic, cross-sectional side view of amicroelectronic substrate 210 prior to electrolytic processing inaccordance with an embodiment of the invention. In one aspect of thisembodiment, the microelectronic substrate 210 includes a substratematerial 213, such as an oxide or a low dielectric constant material.The substrate material 213 includes a substrate material surface 217having an aperture 216 formed by conventional processes, such asselective etch processes. A first conductive material 218 is disposed onthe substrate material 213 and can form a barrier layer 214 along thewalls of the aperture 216. A second conductive material 209, such as ablanket fill material, can be disposed on the first conductive material218 to form a fill layer 219. In one embodiment, the first conductivematerial 218 can include tungsten (W) or a tungsten compound, such astungsten nitride (WN_(x)), and the second conductive material 209 caninclude copper or copper alloys such as alloys that include at least 50%copper. In other embodiments, these conductive materials can includeother elements or compounds. In any of these embodiments, the firstconductive material 218 and the second conductive material 209 cancollectively define a conductive portion 211 of the microelectronicsubstrate 210.

To form an isolated conductive line within the aperture 216, the firstconductive material 218 and second conductive material 219 external tothe aperture 216 are typically removed. In one embodiment, the secondconductive material 209 is removed using a CMP process. In otherembodiments, an electrochemical-mechanical polishing (ECMP) process oran electrolytic process is used to remove the second conductive material209. An advantage of electrolytic and ECMP processes is that thedownforce applied to the microelectronic substrate 210 during processingcan be reduced or eliminated. Apparatuses for performing these processesare described in greater detail below with reference to FIGS. 4-9. Inany of these embodiments, the result after completing this portion ofthe process is a microelectronic substrate 210 having the secondconductive material 209 external to the aperture 216 and external to thebarrier layer 214 removed, as is shown in FIG. 2B.

Referring now to FIG. 2B, a process in accordance with one embodiment ofthe invention includes simultaneously, electrolytically removing theportions of the second conductive material 209 and the first conductivematerial 218 that extend beyond the substrate material surface 217 afterthe initial removal process described above with reference to FIG. 2A.Accordingly, in one aspect of this embodiment, an electrolytic liquid231 can be disposed on the microelectronic substrate 210 and a pair ofelectrodes 220 (shown as a first electrode 220 a and a second electrode220 b) can be positioned in electrical communication with theelectrolytic liquid 231. The electrodes 220 can be coupled to a variablesignal transmitter 221 (such as a variable current source) to provide avarying electrical signal to both the first conductive material 218 andthe second conductive material 209. These conductive materials can besimultaneously removed via an electrolytic process.

In a further aspect of this embodiment, the pH of the electrolyticliquid 231 is selected to control the difference between the opencircuit potential of the first conductive material 218 and the opencircuit potential of the second conductive material 209. As used herein,the difference in open circuit potentials between the first conductivematerial 218 and the second conductive material 209 refers to thedifference in electrical potential that would result when measuring thevoltage difference between the first conductive material 218 and thesecond conductive material 209 in the presence of the electrolyticliquid 231, but in the absence of any current applied by the signaltransmitter 221. In a particular aspect of this embodiment, for example,when the first conductive material 218 includes tungsten and the secondconductive material 209 includes copper, the pH of the electrolyticliquid 231 can be selected to be from about 2 to about 5 to produce adifference in open circuit potential of from about 0.50 volts to about−0.50 volts. In other words, the absolute value of the difference inopen circuit potential can be about 0.50 volts or less. In otherembodiments, the absolute value of the difference in open circuitpotential can be about 0.25 volts or less, for example, 0.15 volts orless. In still further embodiments, the pH of the electrolytic liquid231 can have other values to produce near-zero open circuit potentialdifferentials for other combinations of first conductive materials 218and second conductive materials 209. For example, in one embodiment, theelectrolytic liquid 231 can have a pH of from about 0 to about 7.

In any of the foregoing embodiments, the first and second conductivematerials 218, 209 can be removed simultaneously without necessarilybeing removed at the same rates. For example, in one embodiment forwhich the first conductive material 218 includes tungsten or a tungstencompound and the second conductive material 209 includes copper, thecopper can be removed at about four times the rate at which the tungstenor tungsten compound is removed. In other embodiments, the first andsecond conductive materials 218, 209 can be removed at rates that varyby greater or lesser amounts.

In one embodiment, the pH of the electrolytic liquid 231 can becontrolled by disposing an acid in the electrolytic liquid 231.Accordingly, the electrolytic liquid 231 can include a liquid carrier(such as deionized water) and an acid such as nitric acid, acetic acid,hydrochloric acid, sulfuric acid, or phosphoric acid. In otherembodiments, the electrolytic liquid 231 can include other acids. Inaddition to reducing the pH of the electrolytic liquid 231, the acid canprovide ions to enhance the electrolytic action of the electrolyticliquid 231. In any of these embodiments, the electrolytic liquid 231 canalso optionally include an inhibitor, such as benzotriazole (BTA) toproduce more uniform material removal. The electrolytic liquid 231 canalso include oxidizers, such as hydroxylamine, peroxide or ammoniumpersulfate. In another embodiment, the oxidizers can be eliminated, forexample, when the electrolytic action provided by the electrodes 220 issufficient to oxidize the conductive materials 218 and 209.

In any of the foregoing embodiments, the first conductive material 218and the second conductive material 209 external to the recess 216 can beremoved, producing a microelectronic substrate 210 having an embeddedconductive structure 208, as shown in FIG. 2C. In one embodiment, theconductive structure 208 can include a conductive line and in otherembodiments, conductive structure 208 can include a via or other featurein the microelectronic substrate 210. In any of these embodiments, theforegoing processes can provide a conductive structure 208 having asmooth external surface 207 that includes smooth external surfaceportions for both the first conductive material 218 and the secondconductive material 209.

One feature of an embodiment of the method described above withreference to FIGS. 2A-2C is that the pH of the electrolytic liquid 231can be selected to reduce or eliminate the open circuit potentialdifferential between the first conductive material 218 and the secondconductive material 209. An advantage of this feature is that thelikelihood for a galvanic reaction, which can preferentially pit,dissolve, or otherwise remove one of the conductive materials morereadily than the other, can be reduced and/or eliminated. Accordingly,the resulting external surface 207 that includes the first conductivematerial 218 and the second conductive material 209 can be clean anduniform, as shown in FIG. 2C. Another advantage of this feature is thatthe first conductive material 218 and the second conductive material 209can be removed simultaneously without requiring high downforces whichcan damage structures and features of the microelectronic substrate 210.

In the embodiments described above with reference to FIGS. 2A-2C, thefirst and second electrodes 220 a, 220 b are spaced apart from themicroelectronic substrate 210 as they remove conductive materials fromthe microelectronic substrate 210. An advantage of this arrangement isthat the conductive material removal process can be relatively uniform.In other embodiments, one or more of the electrodes can be positioned indirect contact with the microelectronic substrate 210. For example, asshown in FIG. 3, a first electrode 320 a can be positioned in a spacedapart orientation relative to the microelectronic substrate 210, and asecond electrode 320 b can be connected to a rear surface of themicroelectronic substrate 210. A conductive path 308 (such as aninternal via) between the rear surface and the conductive portion 211 ofthe microelectronic substrate can complete the circuit between theelectrodes 320 a, 320 b, allowing the signal transmitter 221 to removeconductive material in a manner generally similar to that describedabove. In still another embodiment, the second electrode 320 b can beconnected directly to the microelectronic substrate 210. Sucharrangements can be used when material removal nonuniformities which mayresult from the direct contact between the electrode and themicroelectronic substrate are remote from regions that might beadversely affected by such nonuniformities.

FIGS. 4-9 illustrate apparatuses for electrolytically,chemically-mechanically, and/or electrochemically-mechanically removingmaterial from microelectronic substrates to perform the processesdescribed above with reference to FIGS. 2A-3. Beginning with FIG. 4, anapparatus 460 can electrolytically remove conductive material from themicroelectronic substrate 210 in accordance with an embodiment of theinvention. In one aspect of this embodiment, the apparatus 460 includesliquid support, such as a vessel 430 containing an electrolytic liquidor gel 431. A support member 440 supports the microelectronic substrate210 relative to the vessel 430 so that the conductive portion 211 of themicroelectronic substrate 210 contacts the electrolytic liquid 431. Inanother aspect of this embodiment, the support member 440 can be coupledto a substrate drive unit 441 that moves the support member 440 and thesubstrate 210 relative to the vessel 430. For example, the substratedrive unit 441 can translate the support member 440 (as indicated byarrow “A”) and/or rotate the support member 440 (as indicated by arrow“B”).

The apparatus 460 can further include a first electrode 420 a and asecond electrode 420 b (referred to collectively as electrodes 420)supported relative to the microelectronic substrate 210 by a support arm424. In one aspect of this embodiment, the support arm 424 is coupled toan electrode drive unit 423 for moving the electrodes 420 relative tothe microelectronic substrate 210. For example, the electrode drive unit423 can move the electrodes 420 toward and away from the conductiveportion 211 of the microelectronic substrate 210, (as indicated by arrow“C”), and/or transversely (as indicated by arrow “D”) in a planegenerally parallel to the conductive portion 211. In other embodiments,the electrode drive unit 423 can move the electrodes 420 in otherfashions, or the electrode drive unit 423 can be eliminated when thesubstrate drive unit 441 provides sufficient relative motion between thesubstrate 210 and the electrodes 420.

In either embodiment described above with reference to FIG. 4, theelectrodes 420 can be coupled to a signal transmitter 421 with leads 428for supplying electrical current to the electrolytic liquid 431 and theconductive portion 211. In operation, the signal transmitter 421 cansupply an alternating current (signal phase or multi-phase) to theelectrodes 420. The current passes through the electrolytic liquid 431and reacts electrochemically with the conductive portion 211 to removematerial (for example, atoms or groups of atoms) from the conductiveportion 211. The electrodes 420 and/or the microelectronic substrate 210can be moved relative to each other to remove material from selectregions of the conductive portion 211, or from the entire conductiveportion 211.

In one aspect of an embodiment of the apparatus 460 shown in FIG. 4, adistance D₁ between the electrodes 420 and the conductive portion 211 isset to be smaller than a distance D₂ between the first electrode 420 aand the second electrode 420 b. Furthermore, the electrolytic liquid 431generally has a higher resistance than the conductive portion 211.Accordingly, the alternating current follows the path of leastresistance from the first electrode 420 a, through the electrolyticliquid 431 to the conductive portion 211 and back through theelectrolytic liquid 431 to the second electrode 420 b, rather than fromthe first electrode 420 a directly through the electrolytic liquid 431to the second electrode 420 b. In one aspect of this embodiment, theresistance of the electrolytic liquid 431 can be increased as thethickness of the conductive portion 211 decreases (and the resistance ofthe conductive portion 211 increases) to maintain the current pathdescribed above. In another embodiment, a low dielectric material (notshown) can be positioned between the first electrode 420 a and thesecond electrode 420 b to decouple direct electrical communicationbetween the electrodes 420 that does not first pass through theconductive portion 211.

FIG. 5 is a partially schematic, side elevation view of an apparatus 560that includes a support member 540 positioned to support themicroelectronic substrate 210 in accordance with another embodiment ofthe invention. In one aspect of this embodiment, the support member 540supports the microelectronic substrate 210 with the conductive portion211 facing upwardly. A substrate drive unit 541 can move the supportmember 540 and the microelectronic substrate 210, as described abovewith reference to FIG. 4. Electrodes 520, including first and secondelectrodes 520 a and 520 b, are positioned above the conductive portion211 and are coupled to a current source 521. A support arm 524 supportsthe electrodes 520 relative to the substrate 210 and is coupled to anelectrode drive unit 523 to move the electrodes 520 over the surface ofthe conductive portion 211 in a manner generally similar to thatdescribed above with reference to FIG. 4.

In one aspect of the embodiment shown in FIG. 5, the apparatus 560further includes an electrolyte vessel 530 having a supply conduit 537with an aperture 538 positioned proximate to the electrodes 520.Accordingly, an electrolytic liquid 531 can be deposited locally in aninterface region 539 between the electrodes 520 and the conductiveportion 211, without necessarily covering the entire conductive portion211. The electrolytic liquid 531 and the conductive material removedfrom the conductive portion 211 flow over the substrate 210 and collectin an electrolyte receptacle 532. The mixture of electrolytic liquid 531and conductive material can flow to a reclaimer 533 that removes most ofthe conductive material from the electrolytic liquid 531. A filter 534positioned downstream of the reclaimer 533 provides additionalfiltration of the electrolytic liquid 531, and a pump 535 returns thereconditioned electrolytic liquid 531 to the electrolyte vessel 530 viaa return line 536.

In another aspect of an embodiment shown in FIG. 5, the apparatus 560can include a sensor assembly 550 having a sensor 551 positionedproximate to the conductive portion 211, and a sensor control unit 552coupled to the sensor 551 for processing signals generated by the sensor551. The control unit 552 can also move the sensor 551 relative to themicroelectronic substrate 210. In a further aspect of this embodiment,the sensor assembly 550 can be coupled via a feedback path 553 to theelectrode drive unit 523 and/or the substrate drive unit 541.Accordingly, the sensor 551 can determine which areas of the conductiveportion 211 require additional material removal and can move theelectrodes 520 and/or the microelectronic substrate 210 relative to eachother to position the electrodes 520 over those areas. Alternatively,(for example, when the removal process is highly repeatable), theelectrodes 520 and/or the microelectronic substrate 210 can moverelative to each other according to a pre-determined motion schedule.

FIG. 6 schematically illustrates an apparatus 660 for electrolytically,chemically-mechanically and/or electrochemically-mechanically polishingthe microelectronic substrate 210 in accordance with an embodiment ofthe invention. In one aspect of this embodiment, the apparatus 660 has asupport table 680 with a top-panel 681 at a workstation where anoperative portion “W” of a polishing pad 683 is positioned. Thetop-panel 681 is generally a rigid plate to provide a flat, solidsurface to which a particular section of the polishing pad 683 may besecured during polishing.

The apparatus 660 can also have a plurality of rollers to guide,position and hold the polishing pad 683 over the top-panel 681. Therollers can include a supply roller 687, first and second idler rollers684 a and 684 b, first and second guide rollers 685 a and 685 b, and atake-up roller 686. The supply roller 687 carries an unused orpreoperative portion of the polishing pad 683, and the take-up roller686 carries a used or postoperative portion of the polishing pad 683.Additionally, the first idler roller 684 a and the first guide roller685 a can stretch the polishing pad 683 over the top-panel 681 to holdthe polishing pad 683 stationary during operation. A motor (not shown)drives at least one of the supply roller 687 and the take-up roller 686to sequentially advance the polishing pad 683 across the top-panel 681.Accordingly, clean preoperative sections of the polishing pad 683 may bequickly substituted for used sections to provide a consistent surfacefor polishing and/or cleaning the microelectronic substrate 210.

The apparatus 660 can also have a carrier assembly 690 that controls andprotects the microelectronic substrate 210 during polishing. The carrierassembly 690 can include a substrate holder 692 to pick up, hold andrelease the microelectronic substrate 210 at appropriate stages of thepolishing process. The carrier assembly 690 can also have a supportgantry 694 carrying a drive assembly 695 that can translate along thegantry 694. The drive assembly 695 can have an actuator 696, a driveshaft 697 coupled to the actuator 696, and an arm 698 projecting fromthe drive shaft 697. The arm 698 carries the substrate holder 692 via aterminal shaft 699 such that the drive assembly 695 orbits the substrateholder 692 about an axis E—E (as indicated by arrow “R₁”). The terminalshaft 699 may also rotate the substrate holder 692 about its centralaxis F—F (as indicated by arrow “R₂”).

The polishing pad 683 and a polishing liquid 689 define a polishingmedium 682 that electrolytically, chemically-mechanically, and/orelectro-chemically-mechanically removes material from the surface of themicroelectronic substrate 210. In some embodiments, the polishing pad683 may be a nonabrasive pad without abrasive particles, and thepolishing liquid 689 can be a slurry with abrasive particles andchemicals to remove material from the microelectronic substrate 210. Inother embodiments, the polishing pad 683 can be a fixed-abrasivepolishing pad in which abrasive particles are fixedly bonded to asuspension medium. To polish the microelectronic substrate 210 with theapparatus 660, the carrier assembly 690 presses the microelectronicsubstrate 210 against a polishing surface 688 of the polishing pad 683in the presence of the polishing liquid 689. The drive assembly 695 thenorbits the substrate holder 692 about the axis E—E and optionallyrotates the substrate holder 692 about the axis F—F to translate thesubstrate 210 across the polishing surface 688. As a result, theabrasive particles and/or the chemicals in the polishing medium 682remove material from the surface of the microelectronic substrate 210 ina chemical and/or chemical-mechanical polishing process.

In a further aspect of this embodiment, the polishing liquid 689 caninclude an electrolyte for electrolytic processing or ECMP processing.In another embodiment, the apparatus 660 can include an electrolytesupply vessel 630 that delivers an electrolyte separately to thepolishing surface 688 of the polishing pad 683 with a conduit 637, asdescribed in greater detail below with reference to FIG. 7. In eitherembodiment, the apparatus 660 can further include a current supply 621coupled to electrodes positioned proximate to the polishing pad 683.Accordingly, the apparatus 660 can electrolytically remove material fromthe microelectronic substrate 210.

FIG. 7 is a partially exploded, partially schematic isometric view of aportion of the apparatus 660 described above with reference to FIG. 6.In one aspect of the embodiment shown in FIG. 6, the top-panel 681houses a plurality of electrode pairs, each of which includes a firstelectrode 720 a and a second electrode 720 b. The first electrodes 720 aare coupled to a first lead 728 a and the second electrodes 720 b arecoupled to a second lead 728 b. The first and second leads 728 a and 728b are coupled to the current supply 621 (FIG. 6). In one aspect of thisembodiment, the first electrodes 720 a can be separated from the secondelectrodes 720 b by an electrode dielectric layer 729 a that includesTeflon™ or another suitable dielectric material. The electrodedielectric layer 729 a can accordingly control the volume and dielectricconstant of the region between the first and second electrodes 720 a and720 b to control the electrical coupling between the electrodes.

The electrodes 720 a and 720 b can be electrically coupled to themicroelectronic substrate 210 (FIG. 6) by the polishing pad 683. In oneaspect of this embodiment, the polishing pad 683 is saturated with anelectrolytic liquid 731 supplied by the supply conduits 637 throughapertures 738 in the top-panel 681 just beneath the polishing pad 683.Accordingly, the electrodes 720 a and 720 b are selected to becompatible with the electrolytic liquid 731. In an another arrangement,the electrolytic liquid 731 can be supplied to the polishing pad 683from above (for example, by disposing the electrolytic liquid 731 in thepolishing liquid 689, rather than by directing the electrolytic liquidupwardly through the polishing pad 683). Accordingly, the apparatus 660can include a pad dielectric layer 729 b positioned between thepolishing pad 683 and the electrodes 720 a and 720 b. When the paddielectric layer 729 b is in place, the electrodes 720 a and 720 b canbe isolated from physical contact with the electrolytic liquid 731 andcan accordingly be selected from materials that are not necessarilycompatible with the electrolytic liquid 731.

FIG. 8 is an isometric view of a portion of an apparatus 860 havingelectrodes 820 (shown as a first electrode 820 a and a second electrode820 b), and a polishing medium 882 arranged in accordance with anotherembodiment of the invention. In one aspect of this embodiment, thepolishing medium 882 includes polishing pad portions 883 that projectbeyond the electrodes 820 a and 820 b. Each polishing pad portion 883can include a polishing surface 888 and a plurality of flow passages 884coupled to a fluid source (not shown in FIG. 8) with a conduit 837. Eachflow passage 884 can have an aperture 885 proximate to the polishingsurface 888 to provide an electrolytic liquid 831 proximate to aninterface between the microelectronic substrate 210 and the polishingsurface 888. In one aspect of this embodiment, the pad portions 883 caninclude recesses 887 surrounding each aperture 885. Accordingly, theelectrolytic liquid 831 can proceed outwardly from the flow passages 884while the microelectronic substrate 210 is positioned directly overheadand remains spaced apart from the electrodes 820. In other embodiments,the polishing pad portions 883 can be applied to other electrodes, suchas those described above with reference to FIGS. 4 and 5 to provide formechanical as well as electromechanical material removed.

The foregoing apparatuses described above with reference to FIGS. 4-8can be used to electrolytically, chemically-mechanically and/orelectrochemically-mechanically process the microelectronic substrate210. When the apparatuses are used to electrolytically orelectrochemically-mechanically process the microelectronic substrate210, they can provide a varying electrical current that passes from theelectrodes, through the conductive material of the microelectronicsubstrate 210 via the electrolytic liquid. For example, as shown in FIG.9, the apparatus can generate a high-frequency wave 904 and cansuperimpose a low-frequency wave 902 on the high-frequency wave 904. Inone aspect of this embodiment, the high-frequency wave 904 can include aseries of positive or negative voltage spikes contained within a squarewave envelope defined by the low-frequency wave 902. Each spike of thehigh-frequency wave 904 can have a relatively steep rise-time slope totransfer charge through the dielectric material to the electrolyticliquid, and a more gradual fall-time slope. The fall-time slope candefine a straight line, as indicated by high-frequency wave 904, or acurved line, as indicated by high-frequency wave 904 a. In otherembodiments, the high-frequency wave 904 and the low-frequency wave 902can have other shapes depending, for example, on the particularcharacteristics of the dielectric material and the electrolytic liquid,the characteristics of the microelectronic substrate 210, and/or thetarget rate at which conductive material is to be removed from themicroelectronic substrate 210.

The methods described above with reference to FIGS. 2A-3 may beperformed with the apparatuses described above with reference to FIGS.4-9 in a variety of manners in accordance with several embodiments ofthe invention. For example, in one embodiment, a single apparatus can beused to electrolytically remove first the second conductive material 209and then the first and second conductive materials 218, 209simultaneously. Alternatively, one apparatus can initially remove thesecond material 209 (e.g., via CMP) and the same or another apparatuscan subsequently remove both the first and second conductive materials218, 209. In either embodiment, both the first an second conductivematerials 218, 209 can be removed simultaneously when they are exposed.In one aspect of both embodiments, the downforce applied to themicroelectronic substrate 210 can be reduced or eliminated duringelectrolytic processing. In another aspect of these embodiments, aselected downforce can be applied to the microelectronic substrate 210during electrolytic processing to supplement the electrolytic removalprocess with a mechanical removal process. The electrolytic removalprocess can also be supplemented with a chemical removal process inaddition to or in lieu of the mechanical removal process.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. A method for processing a microelectronic substrate, comprising:contacting a surface of a microelectronic substrate with an electrolyticliquid, the microelectronic substrate having a first conductive materialand a second conductive material different than the first conductivematerial; selecting a potential difference between a first open circuitpotential of the first conductive material and a second open circuitpotential of the second conductive material; controlling a pH of theelectrolytic liquid to at least facilitate producing the selectedpotential difference; and simultaneously removing at least portions ofthe first and second conductive materials by passing a varyingelectrical signal through the electrolytic liquid and the conductivematerials while the electrolytic liquid contacts the microelectronicsubstrate.
 2. The method of claim 1 wherein the first conductivematerial includes tungsten and the second conductive material includescopper, further wherein selecting a potential difference between thefirst open circuit potential and the second open circuit potentialincludes selecting an absolute value of the potential difference to beabout 0.15 volts or less, and controlling the pH of the electrolyticliquid includes controlling the pH of the electrolytic liquid to be fromabout 2 to about
 5. 3. The method of claim 1 wherein the firstconductive material includes tungsten and the second conductive materialincludes copper, further wherein selecting a potential differencebetween the first open circuit potential and the second open circuitpotential includes selecting an absolute value of the potentialdifference to be about 0.50 volts or less, wherein controlling a pH ofthe electrolytic liquid includes controlling a pH of the electrolyticliquid to be from about 2 to about 5, and wherein simultaneouslyremoving at least portions of the first and second conductive materialsincludes engaging a polishing pad with the microelectronic substrate andmoving at least one of the microelectronic substrate and the polishingpad relative to the other while passing the electrical signal throughthe first and second conductive materials via two spaced apartelectrodes.
 4. The method of claim 1 wherein passing an electricalsignal includes passing an electrical signal from a first electrodespaced apart from the microelectronic substrate, through theelectrolytic liquid to the first and second conductive materials andfrom the first and second conductive materials through the electrolyticliquid to a second electrode spaced apart from the first electrode andspaced apart from the microelectronic substrate.
 5. The method of claim1 wherein passing an electrical signal includes passing an electricalsignal from a first electrode spaced apart from the microelectronicsubstrate, through the electrolytic liquid to the first and secondconductive materials and to a second electrode positioned in contactwith the microelectronic substrate.
 6. The method of claim 1 whereinsimultaneously removing at least portions of the first and secondconductive materials includes removing portions of the first conductivematerial positioned adjacent to the second conductive material.
 7. Themethod of claim 1 wherein simultaneously removing at least portions ofthe first and second conductive materials includes removing tungsten andcopper.
 8. The method of claim 1 wherein simultaneously removing atleast portions of the first and second conductive materials includesremoving at least portions of a barrier layer that includes at least oneof W and WN_(x).
 9. The method of claim 1 wherein simultaneouslyremoving at least portions of the first and second conductive materialsincludes removing the first conductive material at a first rate andremoving the second material at a second rate different than the firstrate.
 10. The method of claim 1 wherein simultaneously removing at leastportions of the first and second conductive materials includes removingat least portions of a conductive layer that includes at least 50%copper.
 11. The method of claim 1 wherein selecting a potentialdifference between the first open circuit potential and the second opencircuit potential includes selecting an absolute value of the potentialdifference to be about 0.15 volts or less.
 12. The method of claim 1wherein selecting a potential difference between the first open circuitpotential and the second open circuit potential includes selecting anabsolute value of the potential difference to be about 0.50 volts orless.
 13. The method of claim 1 wherein selecting a potential differencebetween the first open circuit potential and the second open circuitpotential includes selecting an absolute value of the potentialdifference to be about 0.25 volts or less.
 14. The method of claim 1wherein controlling the pH of the electrolytic liquid includescontrolling the pH to be from about 2 to about
 5. 15. The method ofclaim 1 wherein contacting a surface of the microelectronic substratewith an electrolytic liquid includes contacting the microelectronicsubstrate with an electrolytic liquid that includes at least one of anoxidizer, a corrosion inhibitor and a pH control agent.
 16. The methodof claim 1 wherein simultaneously removing the first conductive materialand the second conductive material includes simultaneously removing abarrier layer material and a blanket fill material.
 17. The method ofclaim 1 wherein selecting a potential difference between the first opencircuit potential and the second open circuit potential includesselecting a potential difference to control a rate at which a galvanicdissolution process removes at least one of the first and secondconductive materials from the microelectronic substrate.
 18. The methodof claim 1, further comprising changing a resistance of the electrolyticliquid as the first and second conductive materials are removed from themicroelectronic substrate.
 19. The method of claim 1, further comprisingincreasing a resistance of the electrolytic liquid as the first andsecond conductive materials are removed from the microelectronicsubstrate.
 20. The method of claim 1, further comprising contacting themicroelectronic substrate with a polishing pad and moving at least oneof the polishing pad and the microelectronic substrate relative to theother while simultaneously removing at least portions of the first andsecond conductive materials.
 21. A method for processing amicroelectronic substrate, comprising: providing a microelectronicsubstrate having a first conductive material and a second conductivematerial different than the first conductive material; disposing on themicroelectronic substrate an electrolytic liquid; selecting a potentialdifference between a first open circuit potential of the firstconductive material and a second open circuit potential of the secondconductive material; controlling a pH of the electrolytic liquid to atleast facilitate producing the selected potential difference; andsimultaneously removing at least portions of the first and secondconductive materials by passing a variable electrical signal through theelectrolytic liquid and the conductive materials while the electrolyticliquid contacts the microelectronic substrate.
 22. The method of claim21 wherein the first conductive material includes at least one oftungsten and WN_(x) and the second conductive material includes copper,further wherein the selected potential difference is about 0.50 volts orless, and controlling a pH of the electrolytic liquid includescontrolling a pH of the electrolytic liquid to be from about 2 to about5.
 23. The method of claim 21 wherein the first conductive materialincludes at least one of tungsten and WN_(x) and the second conductivematerial includes copper, further wherein the selected potentialdifference is about 0.25 volts or less, and controlling a pH of theelectrolytic liquid includes controlling a pH of the electrolytic liquidto be from about 2 to about
 5. 24. The method of claim 21 wherein thefirst conductive material includes tungsten and the second conductivematerial includes copper, further wherein the selected potentialdifference is from about 0.15 volts to about -0.15 volts, andcontrolling a pH of the electrolytic liquid to be from about 2 to about5, and wherein simultaneously removing at least portions of the firstand second conductive materials includes passing a variable electricalcurrent through the electrolytic liquid and the conductive materialswhile engaging a polishing pad with the microelectronic substrate andmoving at least one of the microelectronic substrate and the polishingpad relative to the other while passing the electrical signal throughthe first and second conductive materials via two electrodes spacedapart from the microelectronic substrate.
 25. The method of claim 21wherein passing an electrical signal includes passing an electricalsignal from a first electrode spaced apart from the microelectronicsubstrate, through the electrolytic liquid to the first and secondconductive materials and through the electrolytic liquid to a secondelectrode spaced apart from the first electrode and spaced apart fromthe microelectronic substrate.
 26. The method of claim 21 whereinpassing an electrical signal includes passing an electrical signal froma first electrode spaced apart from the microelectronic substrate,through the electrolytic liquid to the first and second conductivematerials and to a second electrode positioned in contact with themicroelectronic substrate.
 27. The method of claim 21 whereinsimultaneously removing at least portions of the first and secondconductive materials includes removing portions of the first conductivematerial positioned adjacent to the second conductive material.
 28. Themethod of claim 21 wherein simultaneously removing at least portions ofthe first and second conductive materials includes removing tungsten andcopper.
 29. The method of claim 21 wherein simultaneously removing atleast portions of the first and second conductive materials includesremoving the first conductive material at a first rate and removing thesecond material at a second rate different than the first rate.
 30. Themethod of claim 21 wherein the selected potential difference is about0.25 volts or less, and controlling a pH of the electrolytic liquidincludes controlling a pH of the electrolytic liquid to at leastfacilitate producing the selected potential difference.
 31. The methodof claim 21 wherein controlling a pH of the electrolytic liquid includescontrolling a pH of the electrolytic liquid to be from about 2 to about5.
 32. The method of claim 21 wherein disposing an electrolytic liquidincludes disposing an electrolytic liquid that includes at least one ofan oxidizer, an oxidation inhibitor and a pH control agent.
 33. Themethod of claim 21 wherein simultaneously removing the first conductivematerial and the second conductive material includes simultaneouslyremoving a barrier layer material and a blanket fill material.
 34. Themethod of claim 21 wherein disposing an electrolytic liquid includesdisposing an electrolytic liquid that controls a rate at which agalvanic dissolution process removes at least one of the first andsecond conductive materials from the microelectronic substrate.
 35. Themethod of claim 21, further comprising changing a resistance of theelectrolytic liquid as the first and second conductive materials areremoved from the microelectronic substrate.
 36. The method of claim 21,further comprising increasing a resistance of the electrolytic liquid asthe first and second conductive materials are removed from themicroelectronic substrate.
 37. The method of claim 21, furthercomprising contacting the microelectronic substrate with a polishing padand moving at least one of the polishing pad and the microelectronicsubstrate relative to the other while simultaneously removing at leastportions of the first and second conductive materials.
 38. A method forremoving material from a microelectronic substrate, comprising:contacting a surface of a microelectronic substrate with an electrolyticliquid, the microelectronic substrate having a tungsten containingportion and a copper containing portion, selecting an absolute value ofa difference between a first open circuit potential of the tungstencontaining portion and a second open circuit potential of the coppercontaining portion to be about 0.50 volts or less; controlling a pH ofthe electrolytic liquid to be from about 2 to about 5 to at leastfacilitate producing the selected absolute value of the difference; andsimultaneously removing at least part of the copper containing portionand the tungsten containing portion by passing a varying electricalsignal through the electrolytic liquid and the copper containing andtungsten containing portions while the electrolytic liquid contacts themicroelectronic substrate and while the absolute value of the differenceis about 0.50 volts or less.
 39. The method of claim 38 wherein removingat least part of the copper containing portion includes removing atleast part of a conductive line or a conductive via, and whereinremoving at least part of the tungsten containing portion includesremoving at least part of a barrier layer.
 40. The method of claim 38wherein removing at least part of the copper containing portion includesremoving at least part of a portion having about 50% or more copper. 41.The method of claim 38 wherein removing at least part of the tungstencontaining portion includes removing at least part of a portion havingWN_(x).
 42. The method of claim 38 wherein simultaneously removing atleast part of the copper containing portion and part of the tungstencontaining portion includes removing at least part of the tungstencontaining portion at a first rate and removing at least part of thecopper containing portion at a second rate about four times greater thanthe first rate.
 43. The method of claim 38 wherein passing an electricalsignal includes passing an electrical signal from a first electrodespaced apart from the microelectronic substrate through the electrolyticliquid to the copper containing portion and the tungsten containingportion and from the copper containing portion and the tungstencontaining portion through the electrolytic liquid to a second electrodespaced apart from the microelectronic substrate.
 44. The method of claim38 wherein passing an electrical signal includes passing an electricalsignal from a first electrode spaced apart from the microelectronicsubstrate through the electrolytic liquid to the copper containingportion and the tungsten containing portion and from the coppercontaining portion and the tungsten containing portion to a secondelectrode in contact with the microelectronic substrate.
 45. The methodof claim 38, further comprising contacting the microelectronic substratewith a polishing pad and moving at least one of the polishing pad andthe microelectronic substrate relative to the other while simultaneouslyremoving at least part of the copper containing portion and the tungstencontaining portion.
 46. A method for removing material from amicroelectronic substrate, comprising: providing a microelectronicsubstrate having a surface with a recess, a tungsten containing barrierlayer lining the recess and a copper containing material adjacent to thetungsten barrier layer; contacting the microelectronic substrate with anelectrolytic liquid; selecting an absolute value of a difference betweena first open circuit potential of the tungsten containing barrier layerand a second open circuit potential of the copper containing material tobe about 0.50 volts or less; controlling a pH of the electrolytic liquidto be from about 2 to about 5 to at least facilitate producing theselected absolute value of the difference; positioning first and secondelectrodes in electrical communication with the electrolytic liquid, thefirst and second electrodes being spaced apart from the microelectronicsubstrate; and simultaneously removing at least part of the tungstencontaining barrier layer and the copper containing material by passing avarying electrical current from the first electrode through theelectrolytic liquid to the copper containing material and the tungstencontaining barrier layer and through the electrolytic liquid to thesecond electrode while the absolute value of the difference is is about0.50 volts or less.
 47. The method of claim 46 wherein passing a varyingelectrical current includes passing a varying electrical current whilean absolute value of the difference between the first and second opencircuit potentials is about 0.25 volts or less.
 48. The method of claim46 wherein removing at least part of a tungsten containing barrier layerincludes removing at least part of a tungsten containing barrier layerthat has at least one of W and WN_(x).
 49. The method of claim 46wherein removing at least part of the copper containing materialincludes removing at least part of a material having about 50% or morecopper.
 50. The method of claim 46 wherein contacting themicroelectronic substrate with an electrolytic liquid includescontacting the microelectronic substrate with an electrolytic liquidthat includes an acid.
 51. The method of claim 46 wherein contacting themicroelectronic substrate with an electrolytic liquid includescontacting the microelectronic substrate with an electrolytic liquidthat includes at least one of hydrochloric acid, phosphoric acid,sulfuric acid, nitric acid and acetic acid.
 52. The method of claim 46wherein providing a microelectronic substrate includes providing amicroelectronic substrate with the tungsten containing barrier layer andthe copper containing material defining at least one of a line and avia.
 53. The method of claim 46 wherein simultaneously removing at leastpart of the copper containing material and part of the tungstencontaining barrier layer includes removing at least part of the tungstencontaining barrier layer at a first rate and removing at least part ofthe copper containing material at a second rate about four times greaterthan the first rate.
 54. The method of claim 46, further comprisingcontacting the microelectronic substrate with a polishing pad and movingat least one of the polishing pad and the microelectronic substraterelative to the other while simultaneously removing at least part of thecopper containing portion and the tungsten containing portion.